On Feb. 9, 1988, U.S. Pat. No. 4,724,400, entitled "Linear Amplifier" was issued in the name of G. G. Luettgenau to TRW Inc. (the "400 patent"). Such patent is treated herein solely as a publication. The disclosure of the '400 patent as a publication is, however incorporated herein by reference and made a part hereof.
The '400 patent shows and describes a microwave splitter-combiner apparatus comprising a cylindrical stack of vertically superposed circular metallic plates defining within the stack an upper splitter waveguide and a lower combiner waveguide. Each such waveguide comprises a pair of vertically spaced metallic walls and a chamber between and bounded by such walls and providing a passage through which microwaves propagate, the chamber being essentially in the form of a horizontal cylindrical disk. In the splitter wave guide, the microwaves travel through its cylindrical disk chamber from its center radially outward while, in the combiner waveguide, such travel in its chamber is radially inward towards the center of the chamber.
Disposed on a plate member providing a top closure for the mentioned stack is a set of twenty r.f. amplifier operating units each essentially in the shape of a rectangular block. The twenty units are equiangularly spaced in carousel fashion around the top of such member in respective radial planes which are vertical and pass through the vertical axis of the stack.
Each of such twenty r.f. amplifier units is coupled to the splitter wave guide by an input coaxial connector and to the combiner waveguide by an output coaxial connector. In the operation of the apparatus, high frequency electromagnetic energy is fed to the splitter waveguide's center, travels therefrom radially outward through the waveguide's chamber to the twenty input connectors and is then fed upward by them to the twenty amplifiers which operate in parallel to amplify such energy. The amplified energy is then fed via the twenty output connectors to points in the combiner waveguide's chamber which are radially outward of the chamber's center. From those points the energy travels as waves radially inward through the chamber to its center to there be combined and provide an amplified output from the apparatus.
The '400 patent describes the mentioned connectors as each being a semi-rigid coaxial line or lead comprising a hollow cylindrical outer conductor, a center cylindrical conductor coaxial therewithin, and a cylindrical filling or sleeve of dielectric material, the center conductor being greater in length than the outer conductor to provide a tip which extends beyond the front of the outer conductor. In use, each connector is coupled to its associated waveguide by being received (FIGS. 5a and 9) in vertical holes formed in the plates bounding the top and bottom of the waveguide chamber such that the outer and inner conductors make electrical contact with the walls of the holes in, respectively, the upper and lower plates of the waveguide. No further material details are given in the '400 patent regarding the connection of such connectors to their respective wave guides or the manner of their fastening to their associated r.f. amplifiers.
The coaxial connectors described in the '400 patent have the disadvantage in their use in the disclosed splitter-combiner apparatus that, because the inner and outer conductors of such connectors have outer surfaces which are essentially unyielding and are wholly circular cylindrical, and uniform in cross section, it is often difficult to produce a firm, durable and/or reliable electrical contact between such conductors and the walls of the holes in the wave guide plates in which such conductors are received. As another disadvantage, if, it is attempted to improve such electrical contact, by providing a very close or precision fit of the conductors of the connecting in such holes, then, when it is sought to lift the amplifier associated with the connector vertically up and away from the rest of the splitter-combiner in order to, say, perform some act on the amplifier, the fit between the connector conductors and their receptable holes in the wave guide plates may be so tight as to bind the connector conductors in such holes and thereby cause detachment of the connector from the amplifier. If, however, such detachment occurs, the detached connector produces a short circuit a.c. impedance in the wave guide to which it remains connected.